This same assessment can also be found in his book "Pursue and Destroy."

Can anyone who knows about the topics he described tell whether he was accurate in his assessment, or what? He also gives a detailed assessment of the P-51 in his book, as well as touching on other aircraft. I'd like to know how trust-worthy his comments are.

One thing especially, does anyone know about the "60 lbs. of permanent ballast" in the tail of a Bf 109? I have never heard or seen anything mentioned about this from any other source.

I only skimmed through his assesments of the two aircraft and they broadly agree with (even paraphrasing) other allied reports.

Yes,the Bf 109 E did initially carry permanent ballast in the rear of the fuselage. I'd have to check exactly when,but as the E-3/E-4 started to be produced with armour fitted the ballast was reduced or removed.

I would say the ballast issue is really a non-issue.
Various Spitfires carried different amounts of ballast depending on engine and propeller. Later 109s used a piece of armor under the oil cooler to balance the part wooden tails (no tail ballast needed or wanted). I would be willing to bet that quite a few aircraft carried ballast in order to balance modifications. P-39s could not be flown with guns removed or without ammo unless ballast was used. 60lbs of ballast might not be any worse than a more "elegant" solution, like extending the fuselage ( more weight, more surface drag, better finesse ratio, different elevator and rudder response?) or trying to shorten the engine mount.

I've just read the excerpt again. He really does paraphrase some other,earlier,reports almost word for word. You almost wonder whether he actually flew the aircraft himself

The problem with these kind of reports is that they simply profess one person's opinion,clouded by all that person's bias and prejudice.
Eric Brown's "assessments" of various aircraft from all sides provoke similar debate.